How to fix the 'Can't load'-error when a perl script is executing 'use DBD::mysql;' - mysql

Question

For years, I'm running a perl script on my Synology NAS. This script writes to a MariaDB database. I never had any errors. Until the migration to DSM7. This is what happened ...
I never had any problem when using MariaDB5
I migrated my database from MariaDB5 to MariaDB10. I changed the database name and the credentials to make sure my perl script used the MariaDB10 database. Everything worked fine!
I upgraded my Synology NAS to DSM7, following the provided procedure, including the requirement to remove the MariaDB5 package.
Afterwards, I noticed I following error:
Can't load '/usr/local/lib/perl5/vendor_perl/auto/DBD/mysql/mysql.so' for module DBD::mysql: libmariadb.so.3: cannot open shared object file: No such file or directory at /usr/local/lib/perl5/core_perl/DynaLoader.pm line 193.
at ./mysql1_MDB10.pl line 2.
Compilation failed in require at ./mysql1_MDB10.pl line 2.
BEGIN failed--compilation aborted at ./mysql1_MDB10.pl line 2.
To make it easy to debug, I created a test script:
#!/usr/bin/perl
use DBD::mysql;
$solDBIDB = 'DBI:mysql:database=SOLAR2_10;host=127.0.0.1;port=3307';
$DBUser = 'mydbuser';
$DBPass = 'mydbpass';
$dbh = DBI->connect($solDBIDB, $DBUser, $DBPass) || die "Could not connect to database: $DBI::errstr";
$query = "SELECT * FROM SOLAR2_10.SUM_DATA_ITEMS";
$query_handle = $dbh->prepare($query);
# EXECUTE THE QUERY
$query_handle->execute();
I'm using a Synology NAS DS415P with DSM DSM 7.1-42661 Update 2 (latest updates)
Perl is installed as a package (via the Synology Package center)
perl -v provides the following version information: This is perl 5, version 28, subversion 3 (v5.28.3) built for i686-linux
The version of MariaDB10 is 10.3.32-1040
Update after comment #ikegami
I'm able to find the mysql.so file:
-r-xr-xr-x 1 root root 131923 Apr 21 2021 /usr/local/lib/perl5/vendor_perl/auto/DBD/mysql/mysql.so
I'm able to find the various libmariadb.so files:
ls -l in /volume1/#appstore/MariaDB10/usr/local/mariadb10/lib
lrwxrwxrwx 1 root root 15 Nov 23 2021 libmariadb.so -> libmariadb.so.3
-rwxr-xr-x 1 root root 275356 Nov 23 2021 libmariadb.so.3
lrwxrwxrwx 1 root root 15 Nov 23 2021 libmysqlclient_r.so -> libmariadb.so.3
lrwxrwxrwx 1 root root 15 Nov 23 2021 libmysqlclient.so -> libmariadb.so.3
lrwxrwxrwx 1 root root 17 Nov 23 2021 libmysqld.so -> libmariadbd.so.19
drwxr-xr-x 3 root root 4096 Nov 23 2021 mysql
drwxr-xr-x 2 root root 4096 Nov 23 2021 pkgconfig
Additional info:
cpan -l | egrep -i "mysql"
Bundle::DBD::mysql 4.048
DBD::mysql 4.048
DBD::mysql::GetInfo undef
To me, everything looks properly installed ...
What am I missing?